Diffusion Of Antimony Research Articles

XXVII Международный симпозиум Нанофизика и наноэлектроника", Нижний Новгород, 13-16 марта 2023 г. Формирование заряженных вакансий в анионной подрешетке AlAs

The vacancy formation dynamics in doped semicon- ductor heterostructures with quantum dots (QDs) formed in the AlAs anionic sublattice has been studied. A theoretical model that describes the effect of doping on the vacancy generation dynamics is constructed. It is shown that the generation of positively charged arsenic vacancies is more probable than the generation of neutral ones at high hole concentrations. On the other hand, at high electron concentrations, the formation of neutral arsenic vacancies is more efficient than that positively charged ones. It has been experimentally revealed that the vacancy-stimulated high- temperature diffusion of antimony is enhanced (suppressed) in p-(n-)-doped heterostructures with Al(Sb,As)/AlAs QDs.

Influence of atom segregation on the structure and luminescence of InGaAsSb/AlGaAsSb multiple quantum wells

Quaternary Indium gallium arsenic antimony (InGaAsSb) compounds is indispensable as the active layer of diode lasers emitting at 1.75–4.4 μm, which are used in optoelectronic devices. However, the course of the high-temperature instability of the quantum well structure, which is closely related to the diffusion of indium (In) and antimony (Sb) atoms, is still not clear due to the system's complexity. In this paper, the diffusion process of indium and antimony atoms by thermal treatment, and the changes in the structural and optical properties of the InGaAsSb/AlGaAsSb multiple quantum wells (MQWs) were investigated. The InGaAsSb/AlGaAsSb MQWs were treated with a treatment time of 40 s at different annealing temperatures. X-ray diffraction (XRD) and Raman spectra show that with the increase of annealing temperature, the structure of MQWs were destroyed more seriously, and the segregation of indium and antimony becomes more serious. The luminescence characteristics of MQWs with component segregation were investigated by photoluminescence (PL) spectra.

A Study of Antimony Diffusion of DHBTs with Compositionally Graded InGaAsSb Base

A Study of Antimony Diffusion of DHBTs with Compositionally Graded InGaAsSb Base

Characterization and modeling of thermally-induced doping contaminants in high-purity germanium

High purity germanium (HPGe) is the key material for gamma ray detectors production. Its high purity level (⩽2 · 10−4 ppb of doping impurity) has to be preserved in the bulk during the processes needed to form the detector junctions. With the goal of improving the device performance and expanding the application fields, in this paper many alternative doping processes are evaluated, in order to verify their effect on the purity of the material. In more detail, we investigated the electrical activation of contaminating doping defects or impurities inside the bulk HPGe, induced by both conventional and non-conventional surface doping processes, such as boron ion implantation, phosphorus and gallium diffusion from spin-on doping sources, antimony equilibrium diffusion from a remote sputtered source and laser thermal annealing (LTA) of sputtered antimony. Doping defects, thermally-activated during high temperature annealing, were characterized through electrical measurements. A phenomenological model describing the contamination process was developed and used to analyze the diffusion parameters and possible process thermal windows. It resulted that out-of-equilibrium doping processes confined to the HPGe surface have higher possibilities to be successfully employed for the formation of thin contacts, maintaining the pristine purity of the bulk material. Among them, LTA turned out to be the most promising.

Взаимодействие атомов сурьмы с микропорами в кремнии

AbstractThe interaction between Sb atoms and micropores of a getter layer in silicon is studied. The getter layer was obtained via implantation of Sb^+ ions into silicon and subsequent heat treatment processes. The antimony atoms located in the vicinity of micropores are captured by micropores during gettering annealing and lose its electrical activity. The activation energy of capture process to the pores for antimony is lower than that of antimony diffusion in silicon deformation fields around microvoids on the diffusion process.

Interaction between antimony atoms and micropores in silicon

The interaction between Sb atoms and micropores of a getter layer in silicon is studied. The getter layer was obtained via implantation of Sb+ ions into silicon and subsequent heat treatment processes. The antimony atoms located in the vicinity of micropores are captured by micropores during gettering annealing and lose its electrical activity. The activation energy of capture process to the pores for antimony is lower than that of antimony diffusion in silicon deformation fields around microvoids on the diffusion process.

Antimony Diffusion in CdTe

Group V dopants may be used for next-generation high-voltage cadmium telluride (CdTe) solar photovoltaics, but fundamental defect energetics and kinetics need to be understood. Here, antimony (Sb) diffusion is studied in single-crystal and polycrystalline CdTe under Cd-rich conditions. Diffusion profiles are determined by dynamic secondary ion mass spectroscopy and analyzed with analytical bulk and grain-boundary diffusion models. Slow bulk and fast grain-boundary diffusion are found. Density functional theory is used to understand formation energy and mechanisms. The theory and experimental results create new understanding of group V defect kinetics in CdTe.

비정질 및 단결정 실리콘에서 10~50 keV 에너지로 주입된 안티몬 이온의 분포와 열적인 거동에 따른 연구

For the formation of N + doping, the antimony ions are mainly used for the fabrication of a BJT (bipolar junction transistor), CMOS (complementary metal oxide semiconductor), FET (field effect transistor) and BiCMOS (bipolar and complementary metal oxide semiconductor) process integration. Antimony is a heavy element and has relatively a low diffusion coefficient in silicon. Therefore, antimony is preferred as a candidate of ultra shallow junction for n type doping instead of arsenic implantation. Three-dimensional (3D) profiles of antimony are also compared one another from different tilt angles and incident energies under same dimensional conditions. The diffusion effect of antimony showed ORD (oxygen retarded diffusion) after thermal oxidation process. The interfacial effect of a SiO2/Si is influenced antimony diffusion and showed segregation effects during the oxidation process. The surface sputtering effect of antimony must be considered due to its heavy mass in the case of low energy and high dose conditions. The range of antimony implanted in amorphous and crystalline silicon are compared each other and its data and profiles also showed and explained after thermal annealing under inert N2 gas and dry oxidation.

Effects of carbon on phosphorus diffusion in SiGe:C and the implications on phosphorus diffusion mechanisms

The use of carbon (C) in SiGe base layers is an important approach to control the base layer dopant phosphorus (P) diffusion and thus enhance PNP heterojunction bipolar transistor (HBT) performance. This work quantitatively investigated the carbon impacts on P diffusion in Si0.82Ge0.18:C and Si:C under rapid thermal anneal conditions. The carbon molar fraction is up to 0.32%. The results showed that the carbon retardation effect on P diffusion is less effective for Si0.82Ge0.18:C than for Si:C. In Si0.82Ge0.18:C, there is an optimum carbon content at around 0.05% to 0.1%, beyond which more carbon incorporation does not retard P diffusion any more. This behavior is different from the P diffusion behavior in Si:C and the B in Si:C and low Ge SiGe:C, which can be explained by the decreased interstitial-mediated diffusion fraction fIP, SiGe to 95% as Ge content increases to 18%. Empirical models were established to calculate the time-averaged point defect concentrations and effective diffusivities as a function of carbon and was shown to agree with previous studies on boron, phosphorus, arsenic and antimony diffusion with carbon.

Comparison Study on Adsorption and Removal of Antimony from Acidic Aqueous Solution by Activated Carbons and Machine-Made Charcoal

Adsorption effects of three kinds of activated carbons and a type of machine-made charcoal on the removal of antimony from acidic aqueous solution were investigated and compared. With an initial antimony solution concentration of 1000 μgL-1, the antimony adsorption by selected adsorbents were found to descend in the following order: machine-made charcoal (52.4%) > coconut activated carbon (42.6%) > coal based activated carbon (31.1%) > apricot stone based activated carbon (24.6%). The machine-made charcoal has the best adsorption capacity with a maximum adsorption values of 523.76 μgL-1. Five kinetic models were used for the fitting of the process of antimony adsorption, including Elovich, parabola diffusion, second order, first order and double-constant. Results showed that parabola diffusion and double-constant rate equation were the most suitable models in describing the relationship of antimony adsorption with time in acidic aqueous solution, implying that the adsorption kinetics of the antimony by the selected adsorbents in water might be a surface diffusion. Three adsorptive capacity indicators (iodine number, methylene blue number and phenol number) were determined in this paper. However, machine-made charcoal, which has a relatively high adsorption capacity, is of the lowest levels of the adsorptive capacity indicators. Thus, some complex mechanisms might be involved for the antimony adsorption by the machine-made charcoal, consequently considering the mechanism for the adsorption of antimony by the charcoal has not been verified, a further study still needs to be done.

Investigation of antimony diffusion for a local back surface field with laser-fired contacts in crystalline silicon solar cells

We report on a laser-doping process for the formation of a local back surface field with antimony for n-type crystalline silicon solar cells. The local back surface field was formed at low temperature with a laser-fired contact process. A 100 nm thick Sb layer with 44 mW laser power resulted in a junction depth of 500 nm, and a carrier concentration of 5 × 1020 cm−3 yielded the best electrical results, with a current density of 35 mA cm−2 and an efficiency of 17.16%.

Influence of radiation defects on diffusion of arsenic and antimony in implanted silicon

Diffusion of implanted Sb and As in silicon layers with various contents of radiation defects is investigated during furnace thermal annealing and rapid thermal annealing (RTA). The defect concentration was varied by the additional introduction of Si+ ions. As the defect concentration in the layer increases, the antimony diffusivity increases both during lamp annealing and during furnace thermal annealing, which is governed by diffusion over excess vacancies. The As diffusivity increases with an increase in the concentration of radiation defects in the layer during the lamp annealing and decreases during furnace thermal annealing. The increase in the As diffusivity during RTA is attributed to interstitial Si atoms. The observed decrease in the As diffusivity is caused by the impurity capture by excess vacancies as the traps. However, at defect concentrations much higher than the impurity concentration, the As diffusivity increases but remains substantially lower than the intrinsic value. It follows from the results that the rate of intrinsic As diffusion along the interstitial channel is higher than along the vacancy channel.

Composition dependence of Si and Ge diffusion in relaxed Si1−xGex alloys

Diffusion of silicon (Si) and germanium (Ge) in silicon-germanium Si1−xGex-isotope heterostructures with Ge contents x=0, 0.05, 0.25, 0.45, and 0.70 was investigated in a temperature range between 690 and 1270 °C. The concentration profiles of the stable Si-isotopes and Ge-isotopes were recorded by means of time-of-flight secondary ion mass spectrometry. Analysis of the experimental profiles shows that the Si and Ge diffusion coefficients in elemental Si agree within experimental accuracy. However with increasing Ge content the diffusion of Ge gets increasingly faster compared to that of Si. An Arrhenius type temperature dependence of diffusion is observed for all compositions with slightly lower values for the activation enthalpy of Ge compared to Si. The more pronounced Ge diffusion indicates that with increasing Ge concentration the diffusional jumps of Ge atoms become more successful compared to those of Si. This trend is explained with an increasing contribution of vacancies to self-diffusion in Si1−xGex with x. In contrast to earlier results the composition dependence of the activation enthalpy of self-diffusion reveals an upward bowing. A similar composition dependence is reported for the arsenic (As) and antimony (Sb) diffusion in SiGe and is predicted theoretically for the stability of phosphorus-vacancy and arsenic-vacancy pairs in SiGe. The nonlinear behavior seems to be a general trend and accordingly mainly a consequence of the SiGe alloy system.

Thermal stability of undoped polycrystalline silicon layers on antimony and boron-doped substrates

The structure of as-deposited and annealed polycrystalline silicon layers has been investigated by scanning electron microscopy and x-ray diffraction. The structure of intentionally undoped layers prepared by low pressure chemical vapor deposition at a temperature of 640 °C was found to be stable upon annealing at temperatures lower than about 900 °C. On the other hand, primary recrystallization of the layers has been observed during annealing at temperatures in the range of 900 to 1150 °C. Isochronal annealing revealed the activation energy for the primary recrystallization of undoped layers as 0.6 eV. The activation energy for diffusion of silicon self-interstitials along the grain boundaries was calculated to be 2.2 eV. The difference in grain-growth process was observed for the undoped layers grown either (i) on lightly boron-doped substrate or (ii) on the substrate heavily doped with antimony. The different grain-growth mechanism was found to be a consequence of antimony diffusion into the polycrystalline layer.

Critical issues in the formation of quantum computer test structures by ion implantation

The formation of quantum computer test structures in silicon by ion implantation enables the characterization of spin readout mechanisms with ensembles of dopant atoms and the development of single atom devices. We briefly review recent results in the characterization of spin dependent transport and single ion doping and then discuss the diffusion and segregation behaviour of phosphorus, antimony and bismuth ions from low fluence, low energy implantations as characterized through depth profiling by secondary ion mass spectrometry (SIMS). Both phosphorus and bismuth are found to segregate to the SiO 2/Si interface during activation anneals, while antimony diffusion is found to be minimal. An effect of the ion charge state on the range of antimony ions, 121Sb 25+, in SiO 2/Si is also discussed.

The vacancy in silicon: A critical evaluation of experimental and theoretical results

Recent experimental studies of Shimizu et al. [Phys. Rev. Lett. 98, 095901 (2007)] revealed an activation enthalpy of 3.6 eV for the vacancy contribution to Si self-diffusion. Although this value seems to be in accurate agreement with recent theoretical results, it is at variance with experiments on vacancy-mediated dopant diffusion in Si. In the present study we review results from electronic structure calculations and conclude that the calculations are consistent with an activation enthalpy of 4.5–4.6 eV rather than 3.6 eV for the vacancy contribution to self-diffusion. Moreover, our calculations predict activation enthalpies of 4.45 and 3.81 eV for the vacancy-mediated diffusion of phosphorus and antimony, respectively, in good agreement with the most recent experimental results.

Intrinsic and extrinsic diffusion of phosphorus, arsenic, and antimony in germanium

Diffusion experiments of phosphorus (P), arsenic (As), and antimony (Sb) in high purity germanium (Ge) were performed at temperatures between 600 and 920 °C. Secondary ion mass spectrometry and spreading resistance profiling were applied to determine the concentration profiles of the chemically and electrically active dopants. Intrinsic and extrinsic doping conditions result in a complementary error function and box-shaped diffusion profiles, respectively. These profiles demonstrate enhanced dopant diffusion under extrinsic doping. Accurate modeling of dopant diffusion is achieved on the basis of the vacancy mechanism taking into account singly negatively charged dopant-vacancy pairs and doubly negatively charged vacancies. The activation enthalpy and pre-exponential factor for dopant diffusion under intrinsic condition were determined to 2.85 eV and 9.1 cm2 s−1 for P, 2.71 eV and 32 cm2 s−1 for As, and 2.55 eV and 16.7 cm2 s−1 for Sb. With increasing atomic size of the dopants the activation enthalpy decreases. This is attributed to differences in the binding energy of the dopant-vacancy pairs.

Diffusion of antimony in silicon in the presence of point defects

We have investigated the diffusion of Sb in Si in the presence of defects injected by high-energy implantation of Si ions at room temperature. MeV ion implantation increases the concentrations of vacancies, which induce transient-enhanced diffusion of Sb deposited in Si. We observed a significant enhancement of Sb diffusion. Secondary ions mass spectroscopy has been performed on the implanted samples before and after annealing. Rutherford-backscattering spectrometry has been used to characterize the high-energy implantation damage. By fitting diffusion profiles to a linear diffusive model, information about atomic scale diffusion of Sb, i.e. the generation rate of mobile state Sb and its mean migration length were extracted.

Point defect engineering in preamorphized silicon enriched with fluorine

Fluorine is known to have a beneficial role for the B diffusion reduction in preamorphized Si, and is promising for the realization of ultra-shallow junctions. Thus, we studied the F incorporation in Si during the solid phase epitaxy (SPE) process, pointing out the effects of the implanted F energy and fluence and the role played by the possible presence of dopants. The incorporation of fluorine proceeds by F segregation at the amorphous–crystalline interface, with a kinetics driven by the SPE rate. In fact, the quicker the SPE rate, the higher is the F fluence retained. Moreover, we demonstrated that F incorporated in Si layers does not appreciably affect the Is emission from spatially separated end-of-range (EOR) defects. The modification, induced by the presence of F, of the point defect density (Is and Vs) was also studied by means of B and Sb spike layers, used as local markers for Is and Vs, respectively. We showed that F is not only able to completely suppress the boron transient enhanced diffusion (TED), but can enhance the antimony diffusion. These experimental data demonstrate the ability of F in inducing an Is undersaturation or a Vs supersaturation, ruling out the hypothesis of a chemical bonding between F and the dopants. These results improve the engineering of F-enriched Si, for the realization of ultra-shallow junctions.

ANTIMONY DIFFUSION IN SILICON GEMANIUM ALLOYS UNDER POINT DEFECT INJECTION

Antimony diffusion in in-situ doped strained Si 0.9 Ge 0.1 epitaxial layers, subjected to point defects injection by rapid thermal anneal in oxygen atmosphere, was investigated as a function of temperature at range from 890°C to 1000°C. In this work, the effect of point defect injection on the diffusion of antimony in silicon and silicon-germanium alloys has confirmed the predominant mechanism for diffusion of Sb in Si and SiGe to be vacancy mediated. Diffusivities were obtained using computer simulations. Activation energies were calculated while the diffusivity of antinomy in SiGe under point defect injection as a function of temperature was presented.